Governor with stabilizing means

ABSTRACT

A governor mechanism of the type having interacting flyweights and a governor main spring for regulating engine speed includes damping means comprising hydraulically damped piston means interacting with a compression-extension spring member to temporarily, effectively change the spring rate of the main governor spring, and thereby substantially eliminate governor speed droop while maintaining governor stability.

United States Patent [19] Parks et a1.

[ Oct. 28, 1975 GOVERNOR WITH STABILIZING MEANS [75] Inventors: John H.Parks; Robert H. Miller,

both of Peoria, 111.

[73] Assignee: 'Caterpillar Tractor Co., Peoria, Ill.

[22] Filed: Mar. 20, 1974 [21] App]. No.: 452,822

[52] US. Cl 123/140 FG; 73/522 [51] Int. Cl. F02d 1/04; F02d 1/06 [58]Field of Search 123/140 R, 140 F6, 140 MC; 73/522 [56] References CitedUNITED STATES PATENTS 2,656,174 10/1953 Crookston 73/522 2,868,1841/1959 Moulton 123/140 FG 2,984,112 5/1961 Parks 73/522 3,777,73012/1973 Gates.... 123/140 R 3,795,233 3/1974 Crews 123/140 R FOREIGNPATENTS OR APPLICATIONS 2,064,644 12/1969 Germany 123/140 FG 55,718l/1939 Denmark 123/140 FG Primary Examiner-Charles J. Myhre AssistantExaminerRonald B. Cox Attorney, Agent, or FirmPhi1lips, Moore,Weissenberger Lempio & Strabala [5 7 ABSTRACT A governor mechanism ofthe type having interacting flyweights and a governor main spring forregulating engine speed includes damping means comprising hydraulicallydamped piston means interacting with a compression-extension springmember to temporarily, effectively change the spring rate of the maingovernor spring, and thereby substantially eliminate governor speeddroop while maintaining governor stability.

6 Claims, 1 Drawing Figure U.S. Patent' 0a. 28, 1975 mm mm wm. mm

GOVERNOR WITH STABILIZING MEANS BACKGROUND OF THE INVENTION Thisinvention relates to means for preventing erratic or surging governoroperation of an engine. In particular, this invention relates togovernor damping means for preventing surging or erratic operation ofthe governorcontrolled engine.

Although numerous mechanical and hydromechanical means for preventingsurging or erratic engine operation have been proposed for use inconjunction with conventional governors having interacting spring andflyweight regulating means, many of these have proven unsatisfactory,particularly in applications requiring constant engine speed within alow tolerance and with varying engine loads.

For example, in diesel electric set applications, it is very desirableto achieve isochronous, or near isochronous, governing of the engine toinsure a constant cycIe-per-second output of the generator, typically ofabout 50 or 60 Hz. Due to an engines inherent characteristic of losingspeed when load is applied, a governor is used to increase the amount offuel delivered to the engine when this occurs so that a constant enginespeed is maintained. However, conventional mechanical and certainhydromechanical governors allow engine speed to drop slightly as engineload increases. This characteristic known as speed droop and alsodescribed in Application Ser. No. 202,254, filed Nov. 26, 1971, now U.S.Pat. No. 3,818,883, issued June 25, 1974, to Glassey, is inherent insuch governor designs to insure governor stability, and typicallyresults from the use of a relatively high-rate governor spring. Althoughthis characteristic could be altered by employing a lowerrate governorspring which would interact with the flyweights to provide improvedengine isochrony, the lower-rate spring tends to increase governorinstability, which is detrimental to engine operation. This increase ingovernor instability with lower-rate springs is primarily due to a morerapid reaction of the springs and flyweights to changes in engine load,which causes an overshoot or undershoot of the correct fuel position ofthe fuel control member.

Although other damping means have been proposed for stabilizing engineoperation without increasing governor instability, such as thatdescribed in US. Pat. No. 2,984,112, issued on May 16, 1961 to J. H.Parks and assigned to the assignee hereof, such prior art means have notsatisfactorily provided the desired damping function in allapplications, particularly those requiring constant engine speed withinminimal tolerances.

Therefore, it is desirable to provide improved governor damping meansfor maintaining a predetermined engine speed within minimal tolerancelevels with changes in engine load.

SUMMARY AND OBJECTS OF THE INVENTION The invention provides dampingmeans for governors of the type having interacting flyweights and a maingovernor spring for regulating the position of a fuel control memberwhich controls the supply of fuel to the engine and thus regulates thespeed thereof. The damping means of this invention includehydraulicallydamped piston means interacting with a compressionextensionmember to increase the spring rate of the main governor spring duringtransitory adjustments thereof to engine load changes. Thus, alower-rate governor spring may be employed, and governor speed droopwith increased engine load is substantially eliminated without impairinggovernor stability. Substantially isochronous governing of the enginewithin minimum tolerances is thereby achieved.

It is an object of this invention to provide governor means for engineoperation which prevent surging or erratic operation of thegovernor-controlled engine.

It is another object of this invention to provide governor means forengine operation including means for preventing uncontrolled adjustmentby the governor in response to changes in engine loads.

It is a further object of this invention to provide governor means forenging operation which permit substantially isochronous governing of theengine.

It is an additional object of this invention to provide damping meansfor a governor of the type having interacting flyweights and a maingovernor spring which provide a transitory, effective change in the rateof the governor spring during governor adjustment, thus substantiallyeliminating governor speed droop while maintaining governor stability.

It is yet another object of this invention to provide damping means fora governor which substantially eliminate governor speed droop withoutimpairing governor stability, thereby permitting substantiallyisochronous engine operation within minimum tolerances.

Other objects and advantages of the invention will be apparent from thefollowing description and drawings.

BRIEF DESCRIPTION OF THE DRAWING The sole FIGURE is a sectional view ofa governor mechanism including the governor damping means of thisinvention.

DETAILED DESCRIPTION OF THE INVENTION With reference to the drawing, agovernor mechanism generally indicated at 10 includes a pair offlyweights 1 1 and a main governor spring 12 which interact to controlthe movement of a fuel pump rack bar 13 through a valve member 14 and aservo-mechanism 16. The fuel pump rack bar 13 in turn controls thesupply of fuel to an associated engine (not shown) according to itsposition so that a constant engine speed is maintained. Governor spring12 is disposed between a forward spring seat 17 secured to the valvemember 14, and a rearward spring seat 18 slideably mounted on a guide19. Main governor spring 12 is adjusted to provide the desired enginespeed by adjusting the position of a bifurcated lever 21, one arm 22 ofwhich is shown bearing against rearward spring seat 18 to apply thenecessary force to the main governor spring.

In the conventional governor mechanism thus described, the interactionof the main governor spring 12 and the flyweights 11 control theposition of the fuel pump rack bar 13 through the servo-mechanism 16 ina conventional manner to establish engine speed. When little or no speeddroop is desired, however, the conventional governor is susceptible tosurging or overcontrolled adjustment of the rack bar during changes inengine load, which thereby results in erratic engine operation.

In order to prevent such undesirable surging when substantiallyeliminating engine speed droop in the governor mechanism as engine loadis increased or decreased, while at the same time maintaining stability,the invention provides damping means generally indicated at 23 foreffectively changing the spring rate of main governor spring 12 duringgovernor position changes. The damping means 23 include piston means 24slideably engaged in a bore 25 of the guide 19, and acompression-extension member in the form of a damping spring 26 securedat opposite ends thereof to the piston 24 and a shoulder 27 of forwardspring seat 17, respectively. Piston means 24 is slidable on a shaft 28which functions in a conventional manner as a governor load control bymeans of a flange 29 engaging a full load stop 30 and a second flange 31engaging a shoulder 32 of rearward spring seat 18.

Bore 25 of guide 19 includes chambers 33, 34 formed by the walls of thebore and piston means 24. Guide 19 is provided with an orifice 35communicating chamber 33 with a reservoir 36 having a source ofhydraulic fluid such as engine oil which acts as a damping fluid for theaction of the piston.

Oil reservoir 36, at atmospheric pressure provides a continuous fluidsupply for chamber 33. Orifice 35 provides a continuous controlled fluidflow between chamber 33 and reservoir 36 as dictated by the piston meansmotion. The damping of the piston is caused by the lubricnt being forcedthrough the orifice between piston 24 and bore 25. There is lubricant ononly one side of piston 24 in chamber 33, the other side of piston 24including chamber 34 is to drain. In this manner, the piston is enabledto move to the left or right as urged by spring 26, but restricted bythe damping action.

To operate the engine at a predetermined speed, the lever 21 ispositioned to accordingly preload the governor spring 12. As anincreased load is placed on the engine, the forces acting on flyweightsl 1 decrease, allowing spring 12 to force forward spring seat 17 to theright to a position as illustrated in the figure, thereby actuatingservo-mechanism 16 through the valve member 14 and positioning the rackbar 13 to increase the supply of fuel to the engine, all in aconventional manner.

Simultaneously with the decrease in force on flyweights ll, therightward movement of forward spring seat 17 moves damping spring 26 andattached piston 24 to the right so that the force of the spring 26 iscombined with the force of the governor spring 12. These forces togetherwith the resistance of piston 24, causes a temporary spring action whichacts like a relatively high spring. Once the governor spring andflyweights are positioned to maintain engine speed with the increasedload, spring 26 returns piston 24 to a neutral, or equilibrium position.

When engine load is suddenly decreased, flyweights 11 are moved radiallyoutwardly by centrifugal forces generated by increased engine speed.This outward movement of flyweights l 1 moves forward spring seat 17leftwardly from the position as shown in the Figure to compress maingovernor spring 12, and reposition rack bar 13 through servo-mechanism16 to reduce the supply of fuel to the engine. The leftward movement ofthe forward spring seat 17 simultaneously compresses the damping springseat 26 against the piston 23. Since the piston 23 is damped by fluid inthe chamber 33, however, the piston resists the urging of the dampingspring 26, and the spring 26 in additive combination with the governorspring 12 thereby temporarily functions as a high-rate spring. As theforce of the main spring 12 approaches the force acting on flyweights ll, the damping spring 26 slowly urges the piston 24 to a position wherespring 26 is in a neutral or equilibrium position.

It may therefore be seen that the invention provides improved means forpreventing erratic engine operation and for maintaining a constantengine speed within minimum tolerances. While the invention has beendescribed in terms of a specific embodiment, it is apparent thatequivalent modifications and embodiments are contemplated by theinvention, and no limitations are intended except as specificallypointed out in the appended claims.

We claim:

I. In an engine governor for maintaining a desired engine speed andhaving a fuel control member for regulating the flow of fuel to anengine, flyweight means for controlling the movement of said fuelcontrol member to position said fuel control member to increase the flowof fuel in response to an increase in engine load, main spring meansmounted adjacent to said flyweight means for assisting movement of saidfuel control member in a direction to increase flow of fuel, said mainspring means having a spring rate, wherein said main spring meanscomprises a main spring, said governor including a spring seat for saidmain spring, said flyweight means comprising flyweights for compressingsaid main spring by said spring seat as engine speed increases, andmeans for temporarily, effectively changing said spring rate of saidmain spring means when engine load is suddenly increased or decreased,and thereby maintaining governor stability, said means for changingcomprising a damping spring and a hydraulically damped piston forproviding a force which subtracts from the force of the main springduring a decrease in engine speed and adds to the force of the mainspring during an increase in engine speed, further including ahydraulically damped piston reciprocable within said bore, and saiddamping spring being fixed to said piston at one end thereof and to saidspring seat at the other end thereof, wherein said piston and said boreform a generally cylindrical chamber on the opposite side of said pistonfrom said damping spring, and further including orifice means forcommunicating said chamber with a hydraulic fluid reservoir and forproviding a controlled flow of hydraulic fluid between said chamber andsaid hydraulic fluid reservoir as dictated by reciprocable motion ofsaid piston, and further including a coaxial shaft attached to saidpiston extending on the opposite side of said piston and stop means onsaid shaft for limiting movement of said shaft and thereby said piston.

2. The governor of claim 1 wherein said stop means comprise a flangestop on opposite ends of said shaft.

3. The governor of claim 2 wherein said stop means comprises a full loadstop positioned so as to contact one of said flange stops when saidpiston and shaft move in a first direction.

4. The governor of claim 3 wherein said stop means further comprise ashoulder on said spring seat positioned so as to contact the other ofsaid flange stops when said pistonand shaft move in a second direction,opposite to said first direction.

5. The governor of claim 4 wherein said damping spring is a coil springand the end of said shaft extending on the spring side of said pistonextends through said coil spring.

6. The governor of claim 5 wherein said governor includes a housing andsaid reservoir is defined by said housing.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENT N0. 3,915 4 DATED October 28 1975 |NV,ENTOR(5) I John H. Parks,et al It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

celumn 1, line 35, after "including" insert --a spindle coaxial withsaid spring seat and having a bore ther-ein,--

Signed and Scaled this A ttes t.

RUTH C. MASON Arresting Officer C. MARSHALL DANN Commissioner ofParenrsand Trademurks

1. In an engine governor for maintaining a desired engine speed andhaving a fuel control member for regulating the flow of fuel to anengine, flyweight means for controlling the movement of said fuelcontrol member to poSition said fuel control member to increase the flowof fuel in response to an increase in engine load, main spring meansmounted adjacent to said flyweight means for assisting movement of saidfuel control member in a direction to increase flow of fuel, said mainspring means having a spring rate, wherein said main spring meanscomprises a main spring, said governor including a spring seat for saidmain spring, said flyweight means comprising flyweights for compressingsaid main spring by said spring seat as engine speed increases, andmeans for temporarily, effectively changing said spring rate of saidmain spring means when engine load is suddenly increased or decreased,and thereby maintaining governor stability, said means for changingcomprising a damping spring and a hydraulically damped piston forproviding a force which subtracts from the force of the main springduring a decrease in engine speed and adds to the force of the mainspring during an increase in engine speed, further including ahydraulically damped piston reciprocable within said bore, and saiddamping spring being fixed to said piston at one end thereof and to saidspring seat at the other end thereof, wherein said piston and said boreform a generally cylindrical chamber on the opposite side of said pistonfrom said damping spring, and further including orifice means forcommunicating said chamber with a hydraulic fluid reservoir and forproviding a controlled flow of hydraulic fluid between said chamber andsaid hydraulic fluid reservoir as dictated by reciprocable motion ofsaid piston, and further including a coaxial shaft attached to saidpiston extending on the opposite side of said piston and stop means onsaid shaft for limiting movement of said shaft and thereby said piston.2. The governor of claim 1 wherein said stop means comprise a flangestop on opposite ends of said shaft.
 3. The governor of claim 2 whereinsaid stop means comprises a full load stop positioned so as to contactone of said flange stops when said piston and shaft move in a firstdirection.
 4. The governor of claim 3 wherein said stop means furthercomprise a shoulder on said spring seat positioned so as to contact theother of said flange stops when said piston and shaft move in a seconddirection, opposite to said first direction.
 5. The governor of claim 4wherein said damping spring is a coil spring and the end of said shaftextending on the spring side of said piston extends through said coilspring.
 6. The governor of claim 5 wherein said governor includes ahousing and said reservoir is defined by said housing.